The fly fishing industry continues to seek an improved balance of properties in fly fishing lines. Durability with low recoil memory on the one hand, and shootability on the other have been difficult to balance. Durability with low recoil memory are generally associated with line flexibility while shootability is generally associated with less flexible or more rigid lines. Lack of durability, associated with brittleness or hardness of the fly line, can result in cracking under the normal stresses encountered in casting a fly line. Shootability, on the other hand, is enhanced by a hard or stiff line. Shootability refers to the line "shooting" through the fly rod guides with less loss of force (through friction) than a more flexible line might encounter, with consequent increase in casting distance. Recoil memory refers to the tendency of a fly line to remain coiled that it assumes when disposed on the fly reel. Memory is generally considered to be directly related to the stiffness of the line.
Various constructions for fly fishing lines are known in the art.
U.S. Pat. No. 3,043,045, issued Jul. 10, 1962 to Martuch describes a fly fishing line comprising a nylon base core treated with a uniform priming coating of an adhesive material. A coating composition comprised of polyvinyl chloride in plasticizers is superimposed over the priming or adhesive coating.
U.S. Pat. No. 4,048,744, issued Sep. 20, 1977 to Chandler describes a fly fishing line having a buoyant tip section formed near the tip of the line. The fishing line is described as comprising a core member made of nylon, polyethylene or silk filaments treated with a priming coating of adhesive material over which is superimposed a coating composition comprising a dispersion of finely divided polyvinyl chloride in plasticizer.
United States Letters Patent No. 5,207,732, issued May 4, 1993 to Stark describes a fly fishing line comprising a core with a coating adherently bonded to the core. The coating is described as comprising a polyvinyl chloride resin with an in situ formed polymer to provide stiffness to the line. The polymer is derived from at least one polymerizable monomer including a polyfunctional acrylic monomer and an initiator. Inclusion of the acrylic polymer is said to improve the combination of properties of durability, shootability and recoil memory.
U.S. Pat. No. 5,296,292, issued Mar. 22, 1994 to Butters describes an elongated cylindrical tensile article made of one or more strands of a monofilament core surrounded by porous polytetrafluoroethylene (PTFE) which may be optionally coated or die sized on the outer surface for smoothness and/or abrasion resistance. The described article is said to be particularly useful for fly-casting lines for fishing.
U.S. Pat. No. 5,437,900, issued on Aug. 1, 1995 to Kuzowski describes porous expanded PTFE having a microstructure of nodes interconnected by fibrils where the surface of the material is modified to have increased hydrophobicity. The modified surface with increased hydrophobicity is said to possibly improve the flotation characteristics of fly fishing lines with an outer surface of porous expanded PTFE.
U.S. Pat. No. 5,625,976, issued on May 6, 1997 to Goodale also describes fly fishing lines and methods for their manufacture. The described lines include a core line portion and a coating comprising a copolymer of olefin, preferably ethylene, and acrylic material. The described lines are said to have a specific gravity of less than 1.0 without the necessity of adding microspheres or blowing agents and are said to be plasticizer free.
Commercially available fly lines manufactured by Fly Fishing Technology Ltd. In the United Kingdom and advertised under the trade designation AIRFLO 7000 TS are said to include a "glass smooth polymer coating" which includes PTFE and liquid lubricants. The fly lines are advertised as having a five year non-crack guarantee with "super floatability" due to the inclusion of PTFE into the outer coating of the line on all floating models. The outer coating of these lines is a urethane combined with the aforementioned PTFE.
The fly fishing industry has continued to experiment with fly line compositions in order to improve various properties such as shootability, durability, floatability and the like. Although progress has been made in this area, further improvements are sought to fulfill a long-felt need.